Among cognitive disorders involving deficits in auditory and visual information processing, Infantile Autism and Developmental Receptive Dysphasia share the similar manifestation of delayed and deviant language development. The diagnosis of these disorders, at present, is based on historical and behavioral criteria, and the etiology of each disorder is as yet unknown. The purpose of this proposal is to investigate the neurophysiological correlates of the areas of information processing believed to be defective in Infantile Autism and Developmental Receptive Dysphasia: specifically, categorization, detection of meaning within a context, temporal discrimination and sequencing, and memory encoding and decoding. The event-related brain potential (ERP) has been extensively used to study these areas of information processing in normal subjects, and it will be used in this proposal to investigate these suggested areas of defective processing. There are several advantages of using the ERP for this purpose: (1) It provides the most direct measure known to date of the neurophysiology of information processing. (2) It is particularly suitable for assessing differences in processing capacities between auditory and visual modalities. (3) It enables the assessment of the speed of information processing. (4) It does not require complex behavioral responses. Delineating the neurobiological defects related to information processing in each disorder will significantly improve our understanding of each disorder, enhance our capacity to make accurate diagnoses, and provide important information about the neurophysiology of language and language disorders.